In the filtration of industrial processing liquids, such liquid pass through a generally continuous filter media within a tank into a vacuum chamber having an outlet connected to a conduit which extends outwardly of the tank and is adapted for connection to a pump for feeding filtered liquids back to a processing apparatus, for illustration. It is known in the art that from time to time there is a build-up of debris and sludge upon the filter media at the area where it covers the open-top inlet to the vacuum chamber to such an extent that there is a greatly reduced flow of filtered liquids through the media and through the outlet of the vacuum chamber. Various automatic means are known based upon a vacuum build-up within the vacuum chamber such that when the vacuum reaches a preset value, a vacuum-responsive valve or switch operates a control mechanism for effecting longitudinal feed of a filter screen which is guidably mounted within the tank for a simultaneous longitudinal incremental feed movement of the filter media such as to present a clean filter media to the open top inlet of the vacuum chamber. Normally, a vacuum release valve functions initially to break the vacuum within the vacuum chamber and in a timed manner energizes the drive mechanism which feeds sprocket chains or the like for advancing the filter screen with the filter media moving therewith.